The Einstein Archives Online Website provides the first online access to Albert Einstein's scientific and non-scientific manuscripts held by the Albert Einstein Archives at the Hebrew University of Jerusalem and to an extensive Archival Database, constituting the material record of one of the most influential intellects in the modern era.

ArXiv is an e-print service in the fields of physics, mathematics, non-linear science and computer science. arXiv is owned, operated and funded by Cornell University, a private not-for-profit educational institution.

NASA's Chandra X-ray Observatory is the most sophisticated X-ray observatory built to date. Chandra is designed to observe X-rays from high-energy regions of the universe, such as the remnants of exploded stars.

"The course explores two revolutions in our perception of the universe. The first was the realization that what we see in the heavens are physical objects. The second revolution was Einstein's realization that this was not the whole truth, space and time are not as straightforward as they first appear..."

The following are review articles on string theory and related topics that can be downloaded (in PDF, postscript, or other formats) from the arXiv preprint server. Except for the first category, the reviews are technical in nature.

This site presents a vivid multimedia adventure unfolding the splendor of the Sun, planets, moons, comets, asteroids, and more. Discover the latest scientific information, or study the history of space exploration, rocketry, early astronauts, space missions, spacecraft through a vast archive of photographs, scientific facts, text, graphics and videos.

A portal is an introductory page for a given topic. It complements the main article of the subject by introducing the reader to key articles, images, and categories that further describe the subject. Here you have the physycs portal of the most famous and complete free web encyclopedia.